add min python requirement; run github action for various python vers…

…ions

.github/workflows/pypi-test.yml

@@ -13,13 +13,18 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [ '3.8', '3.9', '3.10' ]
 
+    name: Python ${{ matrix.python-version }}
     steps:
     - uses: actions/checkout@v2
-    - name: Set up Python 3.9
+    - name: Setup Python
       uses: actions/setup-python@v2
       with:
-        python-version: 3.9
+        python-version: ${{ matrix.python-version }}
+        cache: 'pip'
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip

setup.cfg

@@ -41,7 +41,7 @@ package_dir =
     =src
 
 # Require a min/specific Python version (comma-separated conditions)
-# python_requires = >=3.8
+python_requires = >=3.8
 
 # Add here dependencies of your project (line-separated), e.g. requests>=2.2,<3.0.
 # Version specifiers like >=2.2,<3.0 avoid problems due to API changes in